Engines may include crankcase ventilation systems to vent gases out of the crankcase and into an engine intake manifold to provide evacuation of gases from inside the crankcase in order to reduce degradation of various engine components in the crankcase.
Under certain conditions, crankcase ventilation systems may be monitored to identify breaches in the system. For example, a fresh air hose (breather tube) may become disconnected, an oil cap may be off or loose, a dipstick may be out of position, and/or other seals in the crankcase ventilation system may be broken. Following a crankcase breach, degradation of various components included in the crankcase may occur, or the gases may not be properly ingested into the engine to be rendered innocuous.
Various approaches may be used to monitor crankcase ventilation system integrity. For example, a pressure sensor may be used in the crankcase and a valve in a crankcase vent tube may be opened so that pressure or vacuum changes may be sensed in the crankcase to determine if there is a breach in the system.
In other approaches, a plurality of absolute sensors, e.g., a barometric pressure sensor (BP), a compressor inlet pressure sensor (CIP), a throttle inlet pressure sensor (TIP), a manifold air pressure sensor (MAP), and/or a pressure sensor in a crankcase vent hose, etc., may be used in combination to monitor crankcase ventilation system integrity.
However, the inventors herein have recognized that such approaches may add additional hardware to such monitoring systems, e.g., additional sensors and valves, thus increasing costs and complexity of a crankcase ventilation monitoring system. Additionally, some of these sensors may be underutilized, e.g., the crankcase pressure sensor may only be used for crankcase breach detection, thus limiting the value of such sensors.
Thus, in one approach, to at least partially address these issues, an engine method is provided. The method comprises indicating both crankcase ventilation system degradation and a crankcase oil sump level based on a common crankcase sensor.
In this way, the same sensor information may be used for both crankcase breach detection and oil level determination. For example, a crankcase pressure sensor may be positioned in the crankcase oil sump such that it is immersed in oil during engine operation. Under certain conditions, such as when the crankcase is exposed to atmospheric pressure, the pressure sensor may output pressure correlated primarily (or sometimes only) to the oil in the oil sump, which may be converted to the oil level. Then, under other conditions, such as when the crankcase is sealed (e.g., one or more valves coupling the crankcase to atmosphere are closed) and pressure or vacuum is applied to the crankcase, the pressure sensor may output the sum of the oil sump pressure (pressure due the depth below the liquid surface) and the gas pressure of the crankcase. The gas pressure of the crankcase may then be used to determine if a crankcase breach is present and various actions taken in response thereto.
Thus, in one example, a common crankcase sensor may be used both for detecting crankcase breach and for sensing oil level. In doing so, engine hardware may be reduced, lowering cost and reducing system complexity. Further, by immersing the pressure sensor in engine oil, mechanical damping may be provided by the oil, reducing noise in the pressure signal and improving accuracy of the pressure detection.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.